Methods of Preparing a Catalyst

ABSTRACT

A method comprising a) drying a support material comprising silica at temperature in the range of from about 150° C. to about 220° C. to form a dried support; b) contacting the dried support with methanol to form a slurried support; c) subsequent to b), cooling the slurried support to a temperature of less than about 60° C. to form a cooled slurried support; d) subsequent to c), contacting the cooled slurried support with a titanium alkoxide to form a titanated support; and e) thermally treating the titanated support by heating to a temperature of equal to or greater than about 150° C. for a time period of from about 5 hours to about 30 hours to remove the methanol and yield a dried titanated support.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of and claims priority to U.S. patentapplication Ser. No. 17/699,366 filed Mar. 21, 2022, published as U.S.Patent Application Publication No. 2022/0203333 A1, which is adivisional of and claims priority to U.S. patent application Ser. No.16/237,011 filed Dec. 31, 2018, now U.S. Pat. No. 11,331,650 B2, whichis a divisional of and claims priority to U.S. patent application Ser.No. 14/858,512 filed Sep. 18, 2015, now U.S. Pat. No. 10,213,766 B2, allentitled “Methods of Preparing a Catalyst,” all of which areincorporated by reference herein in their entirety.

TECHNICAL FIELD

The present disclosure relates to catalyst compositions. Morespecifically, the present disclosure relates to methods of preparingolefin polymerization catalyst compositions.

BACKGROUND

Enhancements in preparation methods for olefin polymerization catalystscan reduce the costs associated with catalyst production and improveprocess economics. Thus, there is an ongoing need to develop new methodsof preparing olefin polymerization catalysts.

SUMMARY

Disclosed herein is a method comprising a) drying a support materialcomprising silica at temperature in the range of from about 150° C. toabout 220° C. to form a dried support; b) contacting the dried supportwith methanol to form a slurried support; c) subsequent to b), coolingthe slurried support to a temperature of less than about 60° C. to forma cooled slurried support; d) subsequent to c), contacting the cooledslurried support with a titanium alkoxide to form a titanated support;and e) thermally treating the titanated support by heating to atemperature of equal to or greater than about 150° C. for a time periodof from about 5 hours to about 30 hours to remove the methanol and yielda dried titanated support.

Also disclosed herein is a method comprising: a) drying a silica supportmaterial at temperature in the range of from about 150° C. to about 220°C. to form a dried support; b) contacting the dried support with asolution comprising methanol containing less than 0.1 wt. % water andbasic chromium acetate to form a chrominated, slurried support; c)cooling the chrominated, slurried support to a temperature of less thanabout 60° C. to form a cooled slurried support; d) contacting the cooledslurried support with titanium n-propoxide to form a titanated slurriedsupport; e) thermally treating the titanated slurried support byincreasing the temperature of the titanated support to 60° C. to 70° C.;f) prior to complete removal of methanol, contacting the titanatedslurried support with water in an amount ranging from about 0.1 moles toabout 10 moles per mole of titanium to produce a mixture; g) thermallytreating the mixture by heating the mixture to a temperature of about150° C. to about 220° C. for a time period of from about 5 hours toabout 30 hours to form a precatalyst; and h) calcining the precatalystat a temperature in the range of from about 400° C. to about 1000° C.for a time period of from about 30 minutes to about 24 hours to form apolymerization catalyst.

Also disclosed herein is a method comprising a) drying a silica supportat temperature in the range of from about 150° C. to about 220° C. toform a dried support; b) contacting the dried support with achromium-containing compound to form a chrominated support; c)contacting the chrominated support with a solvent to form a slurriedsupport; d) cooling the slurried support to a temperature of less thanabout 60° C. to form a cooled support; e) contacting the cooled supportwith a titanium-containing compound to form a titanated support; f)thermally treating the titanated support by increasing the temperatureof the titanated support to the boiling point of the solvent; g) priorto reaching the boiling point of the solvent, contacting the titanatedsupport with water in an amount ranging from about 0.1 moles to about 10moles per mole of titanium to produce a mixture; h) thermally treatingthe mixture by heating the mixture to a temperature of about 150° C. fora time period of from about 5 hours to about 30 hours to form aprecatalyst; and i) calcining the precatalyst at a temperature in therange of from about 400° C. to about 1000° C. for a time period of fromabout 30 minutes to about 24 hours to form a polymerization catalyst.

BRIEF DESCRIPTION OF THE DRAWINGS

The FIGURE depicts a thermogravimetric analysis of the samples ofexample 2.

DETAILED DESCRIPTION

Disclosed herein are methods for the preparation of a polymerizationcatalyst. In an embodiment, the method comprises contacting asilica-support, titianium alkoxide, and basic chromium acetate underconditions suitable for the formation of a polymerization catalyst. Inan embodiment, a polymerization catalyst produced as disclosed hereinresults in lower emissions of volatile organic compounds (VOCs) duringproduction (e.g., activation via calcination) when compared to anotherwise similar catalyst and are designated lower emitting catalysts(LECs).

In an embodiment, a LEC comprises a silica-support. A silica-supportsuitable for use in the present disclosure may have a surface area andpore volume effective to provide for the production of an activecatalyst (e.g., a LEC). In an embodiment, the silica-support possesses asurface area in the range of from about 250 m²/gram to about 1000m²/gram, alternatively from about 250 m²/gram to about 700 m²/gram,alternatively from about 250 m²/gram to about 600 m²/gram, oralternatively greater than 250 m²/gram. The silica-support may befurther characterized by a pore volume of greater than about 1.0cm³/gram, or alternatively greater than about 1.5 cm³/gram. In anembodiment, the silica-support is characterized by a pore volume rangingfrom about 1.0 cm³/gram to about 2.5 cm³/gram. The silica-support may befurther characterized by an average particle size of from about 10microns to about 500 microns, alternatively about 25 microns to about300 microns, or alternatively about 40 microns to about 150 microns.Generally, the average pore size of the silica-support ranges from about10 Angstroms to about 1000 Angstroms. In one embodiment, the averagepore size of the silica-support material is in the range of from about50 Angstroms to about 500 Angstroms, while in yet another embodiment theaverage pore size ranges from about 75 Angstroms to about 350 Angstroms.

The silica-support may contain greater than about 50 percent (%) silica,alternatively greater than about 80% silica, alternatively greater thanabout 95% silica by weight of the silica-support material. Thesilica-support may be prepared using any suitable method, for examplethe silica-support may be prepared synthetically by hydrolyzingtetrachlorosilane (SiCl₄) with water or by contacting sodium silicatewith a mineral acid. An example of silica-support suitable for use inthis disclosure includes without limitation ES70 which is asilica-support material with a surface area of 300 m²/g, and a porevolume of 1.6 cc/g that is commercially available from PQ Corporation.The silica-support may include additional components that do notadversely affect the LEC, such as zirconia, alumina, thoria, magnesia,fluoride, sulfate, phosphate, or mixtures thereof.

The silica-support may be present in the LEC in an amount of from about50 weight percent (wt. %) to about 99 wt. %, or alternatively from about80 wt. % to about 99 wt. %. Herein the percentage of silica-supportrefers to the final weight percent of silica-support associated with thecatalyst by total weight of the catalyst after all processing steps(e.g., after final activation via calcination).

In an embodiment, a LEC comprises titanium. The source of the titaniummay be a titanium-containing compound such as a titanium tetraalkoxide.In an embodiment, the titanium-containing compound is titaniumn-propoxide Ti(OnPr)₄.

The amount of titanium present in the LEC may range from about 0.1 wt. %to about 10 wt. % titanium by weight of the LEC, alternatively fromabout 0.5 wt. % to about 5 wt. % titanium, alternatively from about 1wt. % to about 4 wt. %, or alternatively from about 2 wt. % to about 4wt. %. In another embodiment, the amount of titanium may range fromabout 1 wt. % to about 5 wt. %. Herein, the percentage titanium refersto the final weight percent titanium associated with the catalystcomposition by total weight of the catalyst composition after allprocessing steps (e.g., after final activation via calcination).

In an embodiment, a LEC comprises chromium. The source of the chromiummay be any chromium-containing compound that is substantially soluble inmethanol. Herein, “substantially soluble” refers to a solubility of atleast 0.1 grams/liter. Nonlimiting examples of chromium-containingcompounds suitable for use in the present disclosure include basicchromium acetate, chromium acetate, chromium (III) nitrate nonahydrate,chromium trioxide, and t-butyl chromate. In an embodiment, the LECcomprises basic chromium acetate.

The amount of chromium present in the catalyst may range from about 0.1wt. % to about 10 wt. % by weight of the LEC, alternatively from about0.25 wt. % to about 3 wt. %, or alternatively from about 0.5 wt. % toabout 1.5 wt. %. Herein, the percentage chromium refers to the finalpercent chromium associated with the support material by total weight ofthe material after all processing steps (e.g., after final activationvia calcination).

In an embodiment, a method for preparation of a LEC comprises drying thesilica-support. Drying of the silica-support can be carried out in atemperature range of from about 150° C. to about 500° C., alternativelyfrom about 150° C. to about 300° C., or alternatively from about 150° C.to about 220° C. for a time period ranging from about 5 hours to about24 hours, or alternatively from about 5 hours to about 12 hours. Dryingof the support material may be carried out in an inert atmosphere (e.g.under vacuum, He, Ar, or nitrogen gas). The resulting material is termeda dried support. The dryness of the silica-support can be measured asloss in weight upon drying at a temperature of 250° C. In an embodiment,the loss on drying of the dried support is less than about 3 wt. %,alternatively less than about 2 wt. %, or alternatively less than about1 wt. %.

In an embodiment, the method for preparation of a LEC further comprisesslurrying the dried support with dry methanol. Herein, “dry methanol”refers to methanol having a water content of less than about 0.1 wt. %.The dried support may be slurried by contact with dry methanol in anamount that ranges from about 1 to about 10 times the total weight ofthe dried support, or alternatively from about 2 to about 3 times thetotal weight of the dried support. The resulting material is termed aslurried dried support.

In an embodiment, the method for preparation of a LEC further comprisescooling the slurried dried support. The slurried dried support may becooled to a temperature of less than about ° C., alternatively less thanabout 60° C., or alternatively less than about 50° C. The resultingmaterial is termed a cooled slurried dried support.

In an embodiment, the method for preparation of a LEC further comprisesaddition of a titanium alkoxide, to the cooled slurried dried support toproduce a titanated cooled slurried dried support. The titanium alkoxidemay comprise equal to or less than twenty-four carbon atoms. Nonlimitingexamples of titanium alkoxides suitable for use in the presentdisclosure include titanium alkoxides comprising linear alkyl chains. Inan embodiment, the titanium alkoxide excludes branched alkyl chains. Inan embodiment, the titanium alkoxide comprises titanium n-propoxide(i.e., Ti(OnPr)₄), titanium n-butoxide (i.e., Ti(OnBu)₄), orcombinations thereof. Titanium may be directly added to the cooledslurried dried support with vigorous mixing such that the titanium isefficiently dispersed throughout the slurry. Upon addition of thetitanium alkoxide to the cooled slurried dried support the resultingmixture may be stirred at ambient temperature for a time period rangingfrom about 5 minutes to about 30 hours, alternatively from about 15minutes to about 12 hours, or alternatively from about 30 minutes toabout 5 hours.

In an embodiment, the method for preparation of a LEC further comprisesaddition of a chromium-containing compound (e.g., basic chromiumacetate) to the titanated cooled slurried dried support. The resultingmaterial is termed a metallated slurried support.

In an embodiment, the method for preparation of a LEC further comprisesaddition of a chromium-containing compound (e.g., basic chromiumacetate) to the cooled slurried dried support. The resulting material istermed a chrominated cooled slurried dried support. The chrominatedcooled slurried dried support may then be contacted with a titaniumcontaining compound (e.g, Ti(OnPr)₄) as disclosed herein to produce atitanated chrominated cooled slurried dried support.

In an alternative embodiment, the method for preparation of a LEC maycomprise addition of a chromium-containing compound (e.g., basicchromium acetate) to the dried support to result in a chrominated driedsupport. The chrominated dried support may then be slurried to produce aslurried chrominated dried support. The slurried chrominated driedsupport may then be cooled as described herein to produce a cooledslurried chrominated dried support. The cooled slurried chrominateddried support may then be contacted with a titanium containing compound(e.g, Ti(OnPr)₄) as disclosed herein to produce a titanated cooledslurried chrominated dried support.

In yet another embodiment, the method for preparation of a LEC furthercomprises addition of a chromium-containing compound (e.g., basicchromium acetate) to the slurried dried support resulting in achrominated slurried dried support. The chrominated slurried driedsupport may subsequently be cooled as described herein to produce acooled chrominated slurried dried support. The cooled chrominatedslurried dried support may then be contacted with a titanium containingcompound (e.g, Ti(OnPr)₄) as disclosed herein to produce a titanatedcooled chrominated slurried dried support.

Herein, chrominated titanated cooled slurried dried support, titanatedchrominated cooled slurried dried support, titanated cooled slurriedchrominated dried support, and titanated cooled chrominated slurrieddried support are collectively referred to as metallated supports.

In each of the foregoing embodiments that result in the production of ametallated support, it is to be understood that processing conditionssimilar to those previously disclosed herein (e.g., mixing times,stirring times, heating times, cooling times, cooling temperatures,etc.) can be applied. In an embodiment, for each of the disclosedmethods of preparation of a metallated support the processing conditionsdescribed herein are applied.

In various embodiments, the chromium-containing compound (e.g., basicchromium acetate) may be added at any point in the process after dryingthe silica and prior to complete removal of the methanol. In someembodiments, the chromium-containing compound (e.g., basic chromiumacetate) can be dissolved in the methanol solvent before slurrying thesilica.

In an embodiment, a method of preparing a LEC further comprisessubjecting the metallated slurried support to a thermal treatment. In anembodiment, the thermal treatment comprises heating the metallatedslurried support to a temperature near the boiling point of methanol(i.e., from about 60° C. to about 70° C.). The method of the presentdisclosure further comprises the addition of water to the metallatedslurried support prior to and/or during thermal treatment and prior tothe complete removal of the methanol. Herein, “complete removal” of theremoval of the methanol refers to less than about 10 volume percent (10vol. %) of the original methanol volume remaining, alternatively lessthan about 9 vol. %, alternatively less than about 8 vol. %,alternatively less than about 7 vol. %, alternatively less than about 6vol. %, alternatively less than about 5 vol. %, alternatively less thanabout 4 vol. %, alternatively less than about 3, alternatively less thanabout 2 vol. %, or alternatively less than about 1 vol. %. Water may beadded to the metallated slurried support in an amount ranging from about0.1 mole to about 10 moles per mole of titanium, alternatively fromabout 1 mole to about 8 moles, or alternatively from about 2 moles toabout 5 moles. The material resulting from the addition of water andheating to from about 60° C. to about 70° C. is termed the hydratedmetallated support.

In an embodiment, the metallated slurried support may be subjected tothermal treatment at a temperature of at least about 150° C.,alternatively from about 150° C. to about 300° C., or alternatively fromabout 150° C. to about 220° C. for a time period of from about 5 hoursto about 30 hours, or alternatively from about 5 hours to about 15hours, or alternatively from about 5 hours to about 8 hours. In anembodiment, water may be added to the metallated slurried support at anypoint after the addition of titanium to also produce a hydratedmetallated support. The water may be added in any form, i.e. solid,liquid, vapor, or solution.

The hydrated metallated support may then be subjected to further thermaltreatment at a temperature of at least about 150° C., alternatively fromabout 150° C. to about 300° C., or alternatively from about 150° C. toabout 220° C. for a time period of from about 5 hours to about 30 hours,or alternatively from about 5 hours to about 15 hours, or alternativelyfrom about 5 hours to about 8 hours. The resulting material is termedthe dried precatalyst.

In an embodiment, the dried precatalyst is heat treated (i.e., calcined)to form a LEC. Heat treatment of the dried precatalyst may be carriedout using any suitable method, e.g., fluidization. Without wishing to belimited by theory, heat treatment of the dried precatalyst may result inan increase in the amount of hexavalent chromium present in thecatalyst. In an embodiment, heat treatment of the dried precatalyst iscarried out in any suitable atmosphere, such as air, oxygen, inert gases(e.g., Ar), or carbon monoxide by heating to a temperature of from about400° C. to about 1000° C., alternatively from about 450° C. to about900° C., alternatively from about 500° C. to about 800° C., oralternatively from about 500° C. to about 700° C. Heat treatment may becarried out for a period of time ranging from about 30 minutes to about24 hours, alternatively from about 1 hour to about 12 hours, oralternatively from about 4 hours to about 12 hours.

In an embodiment, one or more of the steps described previously hereinfor the preparation of a LEC may be carried out in a reactor or reactorsystem. In an alternative embodiment, one or more of the steps describedpreviously herein for the preparation of a LEC may be carried outoutside of a reactor or reactor system. In such embodiments, one or morepreparation parameters (e.g., heat treatment of the dried precatalyst)may be adjusted to facilitate formation of the LEC.

In an embodiment, a method of preparing a LEC of the type disclosedherein comprises obtaining a prepared Cr—Si/Ti precatalyst. The preparedCr—Si/Ti precatalyst may be slurried in methanol to produce a slurriedprecatalyst. The slurried precatalyst may further be subjected to athermal treatment. In an embodiment, the thermal treatment comprisesheating the slurried precatalyst at a temperature of at least about 150°C., alternatively from about 150° C. to about 300° C., or alternativelyfrom about 150° C. to about 220° C. for a time period of from about 5hours to about 30 hours, or alternatively from about 5 hours to about 15hours, or alternatively from about 5 hours to about 8 hours. Theresulting material is termed the dried precatalyst. In an embodiment,the dried precatalyst is heat treated (i.e., calcined) to form a LEC.

The method of the present disclosure further comprises the addition ofwater to the slurried precatalyst. Water may be added to the slurriedcatalyst in an amount ranging from about 0.1 mole to about 10 moles permole of titanium, alternatively from about 1 mole to about 8 moles, oralternatively from about 2 moles to about 5 moles. The water may beadded in any form, i.e. solid, liquid, vapor, or solution.

The catalysts of the present disclosure (i.e., LECs) are suitable foruse in any olefin polymerization method, using various types ofpolymerization reactors. In an embodiment, a polymer of the presentdisclosure is produced by any olefin polymerization method, usingvarious types of polymerization reactors. As used herein,“polymerization reactor” includes any reactor capable of polymerizingolefin monomers to produce homopolymers and/or copolymers. Homopolymersand/or copolymers produced in the reactor may be referred to as resinand/or polymers. The various types of reactors include, but are notlimited to those that may be referred to as batch, continuous, slurry,gas-phase, solution, high pressure, tubular, autoclave, or other reactorand/or reactors. Gas phase reactors may comprise fluidized bed reactorsor staged horizontal reactors. Slurry reactors may comprise verticaland/or horizontal loops. High pressure reactors may comprise autoclaveand/or tubular reactors. Reactor types may include batch and/orcontinuous processes. Continuous processes may use intermittent and/orcontinuous product discharge or transfer. Processes may also includepartial or full direct recycle of un-reacted monomer, un-reactedcomonomer, catalyst and/or co-catalysts, diluents, and/or othermaterials of the polymerization process.

Polymerization reactor systems of the present disclosure may compriseone type of reactor in a system or multiple reactors of the same ordifferent type, operated in any suitable configuration. Production ofpolymers in multiple reactors may include several stages in at least twoseparate polymerization reactors interconnected by a transfer systemmaking it possible to transfer the polymers resulting from the firstpolymerization reactor into the second reactor. Alternatively,polymerization in multiple reactors may include the transfer, eithermanual or automatic, of polymer from one reactor to subsequent reactoror reactors for additional polymerization. Alternatively, multi-stage ormulti-step polymerization may take place in a single reactor, whereinthe conditions are changed such that a different polymerization reactiontakes place.

The desired polymerization conditions in one of the reactors may be thesame as or different from the operating conditions of any other reactorsinvolved in the overall process of producing the polymer of the presentdisclosure. Multiple reactor systems may include any combinationincluding, but not limited to multiple loop reactors, multiple gas phasereactors, a combination of loop and gas phase reactors, multiple highpressure reactors or a combination of high pressure with loop and/or gasreactors. The multiple reactors may be operated in series or inparallel. In an embodiment, any arrangement and/or any combination ofreactors may be employed to produce the polymer of the presentdisclosure.

According to one embodiment, the polymerization reactor system maycomprise at least one loop slurry reactor. Such reactors arecommonplace, and may comprise vertical or horizontal loops. Monomer,diluent, catalyst system, and optionally any comonomer may becontinuously fed to a loop slurry reactor, where polymerization occurs.Generally, continuous processes may comprise the continuous introductionof a monomer, a catalyst, and/or a diluent into a polymerization reactorand the continuous removal from this reactor of a suspension comprisingpolymer particles and the diluent. Reactor effluent may be flashed toremove the liquids that comprise the diluent from the solid polymer,monomer and/or comonomer. Various technologies may be used for thisseparation step including but not limited to, flashing that may includeany combination of heat addition and pressure reduction; separation bycyclonic action in either a cyclone or hydrocyclone; separation bycentrifugation; or other appropriate method of separation.

Typical slurry polymerization processes (also known as particle-formprocesses) are disclosed in U.S. Pat. Nos. 3,248,179, 4,501,885,5,565,175, 5,575,979, 6,239,235, 6,262,191 and 6,833,415, for example;each of which are herein incorporated by reference in their entirety.

Suitable diluents used in slurry polymerization include, but are notlimited to, the monomer being polymerized and hydrocarbons that areliquids under reaction conditions. Examples of suitable diluentsinclude, but are not limited to, hydrocarbons such as propane,cyclohexane, isobutane, n-butane, n-pentane, isopentane, neopentane, andn-hexane. Some loop polymerization reactions can occur under bulkconditions where no diluent is used. An example is polymerization ofpropylene monomer as disclosed in U.S. Pat. No. 5,455,314, which isincorporated by reference herein in its entirety.

According to yet another embodiment, the polymerization reactor maycomprise at least one gas phase reactor. Such systems may employ acontinuous recycle stream containing one or more monomers continuouslycycled through a fluidized bed in the presence of the catalyst underpolymerization conditions. A recycle stream may be withdrawn from thefluidized bed and recycled back into the reactor. Simultaneously,polymer product may be withdrawn from the reactor and new or freshmonomer may be added to replace the polymerized monomer. Such gas phasereactors may comprise a process for multi-step gas-phase polymerizationof olefins, in which olefins are polymerized in the gaseous phase in atleast two independent gas-phase polymerization zones while feeding acatalyst-containing polymer formed in a first polymerization zone to asecond polymerization zone. One type of gas phase reactor is disclosedin U.S. Pat. Nos. 4,588,790, 5,352,749, and 5,436,304, each of which isincorporated by reference in its entirety herein.

According to still another embodiment, a high pressure polymerizationreactor may comprise a tubular reactor or an autoclave reactor. Tubularreactors may have several zones where fresh monomer, initiators, orcatalysts are added. Monomer may be entrained in an inert gaseous streamand introduced at one zone of the reactor. Initiators, catalysts, and/orcatalyst components may be entrained in a gaseous stream and introducedat another zone of the reactor. The gas streams may be intermixed forpolymerization. Heat and pressure may be employed appropriately toobtain optimal polymerization reaction conditions.

According to yet another embodiment, the polymerization reactor maycomprise a solution polymerization reactor wherein the monomer iscontacted with the catalyst composition by suitable stirring or othermeans. A carrier comprising an organic diluent or excess monomer may beemployed. If desired, the monomer may be brought in the vapor phase intocontact with the catalytic reaction product, in the presence or absenceof liquid material. The polymerization zone is maintained attemperatures and pressures that will result in the formation of asolution of the polymer in a reaction medium. Agitation may be employedto obtain better temperature control and to maintain uniformpolymerization mixtures throughout the polymerization zone. Adequatemeans are utilized for dissipating the exothermic heat ofpolymerization.

Polymerization reactors suitable for the present disclosure may furthercomprise any combination of at least one raw material feed system, atleast one feed system for catalyst or catalyst components, and/or atleast one polymer recovery system. Suitable reactor systems for thepresent disclosure may further comprise systems for feedstockpurification, catalyst storage and preparation, extrusion, reactorcooling, polymer recovery, fractionation, recycle, storage, loadout,laboratory analysis, and process control.

Conditions that are controlled for polymerization efficiency and toprovide polymer properties include, but are not limited to temperature,pressure, type and quantity of catalyst or co-catalyst, and theconcentrations of various reactants. Polymerization temperature canaffect catalyst productivity, polymer molecular weight and molecularweight distribution. Suitable polymerization temperatures may be anytemperature below the de-polymerization temperature, according to theGibbs Free Energy Equation. Typically, this includes from about 60° C.to about 280° C., for example, and/or from about 70° C. to about 110°C., depending upon the type of polymerization reactor and/orpolymerization process.

Suitable pressures will also vary according to the reactor andpolymerization process. The pressure for liquid phase polymerization ina loop reactor is typically less than 1000 psig (6.9 MPa). Pressure forgas phase polymerization is usually at about 200 psig (1.4 MPa)-500 psig(3.45 MPa). High pressure polymerization in tubular or autoclavereactors is generally run at about 20,000 psig (138 MPa); to 75,000 psig(518 MPa). Polymerization reactors can also be operated in asupercritical region occurring at generally higher temperatures andpressures. Operation above the critical point of a pressure/temperaturediagram (supercritical phase) may offer advantages.

The concentration of various reactants can be controlled to producepolymers with certain physical and mechanical properties. The proposedend-use product that will be formed by the polymer and the method offorming that product may be varied to determine the desired finalproduct properties. Mechanical properties include, but are not limitedto tensile strength, flexural modulus, impact resistance, creep, stressrelaxation and hardness tests. Physical properties include, but are notlimited to density, molecular weight, molecular weight distribution,melting temperature, glass transition temperature, temperature melt ofcrystallization, density, stereoregularity, crack growth, short chainbranching, long chain branching and rheological measurements.

The concentrations of monomer, co-monomer, hydrogen, co-catalyst,modifiers, and electron donors are generally important in producingspecific polymer properties. Comonomer may be used to control productdensity. Hydrogen may be used to control product molecular weight.Co-catalysts may be used to alkylate, scavenge poisons and/or controlmolecular weight. The concentration of poisons may be minimized, aspoisons may impact the reactions and/or otherwise affect polymer productproperties. Modifiers may be used to control product properties andelectron donors may affect stereoregularity.

Polymers such as polyethylene homopolymers and copolymers of ethylenewith other mono-olefins may be produced in the manner described aboveusing the LECs prepared as described herein. Polymer resins produced asdisclosed herein may be formed into articles of manufacture or end usearticles using techniques known in the art such as extrusion, blowmolding, injection molding, fiber spinning, thermoforming, and casting.For example, a polymer resin may be extruded into a sheet, which is thenthermoformed into an end use article such as a container, a cup, a tray,a pallet, a toy, or a component of another product. Examples of otherend use articles into which the polymer resins may be formed includepipes, films, bottles, fibers, and so forth.

In an embodiment, a LEC prepared as disclosed herein results in areduction in the level of volatile organic compounds (VOCs) producedduring the catalyst preparation. For example, the VOCs may comprisehydrocarbons, aromatic compounds, alcohols, ketones, or combinationsthereof. In an embodiment, the VOCs comprise alkenes, alternativelypropylene, butene, ethylene, or combinations thereof. LECs produced asdisclosed herein may be characterized by VOC emissions that are reducedby from about 50% to about 99% when compared to the emissions from anotherwise similar catalyst. Herein, an “otherwise similar catalyst”refers to a chromium silica-titania catalyst having been prepared usingthe same process, except without the addition of water in the amountsdisclosed herein. Alternatively, emissions of VOCs from LECs prepared asdisclosed herein are reduced by greater than about 50%, alternativelygreater than about 75%, alternatively greater than about 90%, oralternatively greater than about 99% compared to an otherwise similarcatalyst. In an embodiment, the VOC is an alcohol and the LEC hasemissions of from about 50 wt. % to about 1 wt. % based on the weight ofthe LEC, alternatively less than about 20 wt. %, alternatively less thanabout 10 wt. %, or alternatively less than about 1 wt. %.

EXAMPLES

The following examples are given as particular embodiments of thedisclosure and to demonstrate the practice and advantages thereof. It isunderstood that the examples are given by way of illustration and arenot intended to limit the specification or the claims to follow in anymanner.

Melt index (MI, g/10 min) was determined in accordance with ASTM D1238at 190° C. with a 2,160 gram weight. The high load melt index (HLMI) ofa polymer resin represents the rate of flow of a molten resin through anorifice of 0.0825 inch diameter when subjected to a force of 21,600grams at 190° C. The HLMI values are determined in accordance with ASTMD1238 condition E.

Polymerizations were performed in 1.2 L isobutane at 100° C. and 550 psiof ethylene with 5 mL of 1-hexene and run to a productivity of 3200 gPE/g catalyst. The catalyst activity was determined by dividing the massof polymer recovered from the reaction by the amount of catalyst usedand by the active polymerization time.

Examples 1 and 2

Catalysts of the type disclosed herein were prepared and their catalyticproperties investigated. Specifically, a first catalyst, designated I1was prepared using silica gel (14.74 g) that had been dried at 180° C.and was weighed into a flask and placed under a positive pressure of drynitrogen. Enough dry methanol was added to the silica to make a slurry.In a separate flask, basic chromium acetate (0.485 g, 0.8 wt. %) wasdissolved in methanol and then added to the stirred slurry of silicagel. Neat Ti(OnPr)₄ (2.3 mL, 2.7 wt. %) was added dropwise to thestirred slurry of Cr/silica over 5-10 minutes, then the total mixturewas allowed to stir for 15 minutes. The mixture was then heated to 100°C. for 16 hours to completely distill off the methanol and othervolatiles. In the process of heating, water was added to the mixture(0.74 mL, 5 wt. %). After cooling, the dried pre-catalyst was charged toa 1.88 inch diameter activator tube. The pre-catalyst was then calcinedin dry air (1.2-1.6 scfh) at 4° C./min to 650° C. and held at thattemperature for 3 hours to form the active catalyst. A second catalyst,designated 12 was prepared using the method described for thepreparation of I1 without the addition of water.

The catalysts were then used to prepare polymers. Polymerization runswere made in a 2.65 L stainless steel reactor equipped with a marinestirrer rotating at 500 rpm. The reactor was surrounded by a stainlesssteel jacket through which was circulated a stream of hot water, whichpermitted precise temperature control of the reactor to within half adegree centigrade, with the help of electronic control instrumentation.A small amount of the catalyst (0.05 to 0.10 g) was first charged to thereactor under dry nitrogen. Next, approximately 0.6 L of liquidisobutane was added, followed by 5 mL of 1-hexene and additional liquidisobutane to a total of 1.2 L and the reactor heated to the 100° C. settemperature. Ethylene was then added to the reactor, which wasmaintained at 550 psi throughout the course of the experiment. Thereactor was run to a productivity of 3200 g·polyethylene/g·catalyst asdetermined by the flow controllers of the reactor instrumentation basedon ethylene flow to the reactor. After the allotted productivity, theethylene flow to the reactor was stopped and the reactor slowlydepressurized and opened to recover the granular polymer powder. Drypowder was then removed and weighed. Activity was determined from thedry powder weight and the measured time. The HLMI and MI of the polymersproduced from these catalysts were determined and are presented in Table1.

TABLE 1 Activity Catalyst (g/g/h) HILMI MI I1 4923 16.43 0.49 I2 462418.00 0.44

These two runs show that the addition of water after the Ti addition didnot harm the activity or melt index potential of the polymer preparedfrom the catalyst. However, the addition of water did remove undesirablevolatiles during later calcination, as shown in the next example.

Example 3

A dried Cr/silica-titania pre-catalyst (15.87 g) as prepared in exampleI2 was slurried in MeOH (˜50 mL). To the slurry of Cr/silica-titania wasadded water (0.8 mL) and the mixture allowed to stir for 30 min. Themixture was then heated to 100° C. overnight to remove volatilecomponents by distillation and was designated I3.

The dried pre-catalyst treated with water (I3) was compared by TGA tothe same dried pre-catalyst that did not receive water treatment (C1,The FIGURE), and it can be seen that I3 treated with water containssignificantly less volatile organic material than C1. Both the watertreated (I3) and control (C1) pre-catalyst were then activated bycalcination in dry air (1.2-1.6 scfh) at 4° C./min to 650° C. for 3hours to form the active catalyst.

Polymerization results, shown in the table below, again demonstrate nosignificant loss in activity or MI potential from this additional watertreatment, as seen in Table 2.

TABLE 2 Activity Catalyst (g/g/h) HLMI MI I3 5476 12.01 0.24 C1 556310.65 0.21

Example 4

The solubility of alkyl titanates utilized in the preparation of LECswas investigated. To a dry flask under an atmosphere of nitrogen wasadded 625 mg of basic chromium acetate and 30 mL of isopropanol. Themixture was heated to 78° C. for one hour in order to dissolve thechromium, which remained in solution upon cooling. After cooling theresulting green solution to room temperature, 2.8 mL of Ti(OiPr)₄ wasadded with stirring. The solution remained homogeneous for several hoursbefore being used in the preparation of a Cr/silica-titania catalyst.

Basic chromium acetate (625 mg) and 30 mL of methanol at roomtemperature was added to a dry flask under an atmosphere of nitrogen.The chromium readily dissolved to form a green homogeneous solution. Tothis solution was added 2.8 mL of Ti(OiPr)₄. Precipitation of a whitesolid was observed to begin after three minutes demonstrating that thesetitanium alkoxides are not soluble in methanol. While not wishing to bebound by theory, we believe that this is because of rapid exchange ofalkoxy groups to form titanium methoxide groups.

Nevertheless methanol had fewer challenges, because of the ease withwhich it dissolves the chromium acetate, and because of its low boilingpoint, which makes the final catalyst easier to dry. Consequently, theuse of methanol greatly stream-lines the production process. Table 3below shows the boiling points of other non-aqueous solvents capable ofdissolving the chromium salt.

TABLE 3 Organic Solvent Boiling Point Methanol  64.7° C. Ethanol  78.4°C. Isopropanol  82.6° C. n-Propanol  97.0° C. Isobutanol 108.0° C.n-Butanol 117.4° C.

Example 5

A LEC of the type disclosed herein was prepared. Specifically, silicawas dried at a temperature of from about 150° C. to 200° C. for 5 to 24hours. The silica was then slurried in 2 to 3 times its own weight ofdry methanol containing less than 0.1% water. The slurry was then cooledto less than 40° C. Optionally basic chromium acetate can be added tothis slurry, but if temperature is raised to dissolve the Cr, then theslurry must be subsequently cooled before titanium addition. Titaniumn-propoxide was then quickly added to the cooled slurry at highagitation rate to promote fast reaction and the mixture allowed to stirin the cooled state for 1 to 30 hours. Optionally basic chromium acetatecan be added to this slurry at this point in the process. Thetemperature was then raised to 65° C. Water was then added during theheat-up in the amount of 2 to 10 mol per mole of titanium. The mixturewas allowed to stir at 65° C. for 1 to 3 hours. Then the solvent, water,and n-propanol by-product were removed by distillation and the dried at150° C. for 5 to 30 hours to generate a precatalyst. The precatalyst wassubsequently calcined between 400° C. and 1000° C. to generate acatalyst.

ADDITIONAL DISCLOSURE

The following enumerated embodiments are provided as non-limitingexamples.

A first embodiment which is a method comprising: a) drying a supportmaterial comprising silica at temperature in the range of from about150° C. to about 220° C. to form a dried support; b) contacting thedried support with methanol to form a slurried support; c) subsequent tob), cooling the slurried support to a temperature of less than about 60°C. to form a cooled slurried support; d) subsequent to c), contactingthe cooled slurried support with a titanium alkoxide to form a titanatedsupport; and e) thermally treating the titanated support by heating to atemperature of equal to or greater than about 150° C. for a time periodof from about 5 hours to about 30 hours to remove the methanol and yielda dried titanated support.

A second embodiment which is the method of the first embodiment furthercomprising the addition of a chromium-containing compound prior to theremoval of methanol to form a precatalyst.

A third embodiment which is the method of any of the first throughsecond embodiments further comprising the addition of water in an amountranging from about 0.1 to about 10 moles per mole of titanium afteraddition of the titanium alkoxide.

A fourth embodiment which is the method of any of the second throughthird embodiments further comprising calcining the precatalyst at atemperature in the range of from about 400° C. to about 1000° C. for atime period of from about 30 minutes to about 24 hours to form apolymerization catalyst.

A fifth embodiment which is the method of any of the first throughfourth embodiments wherein the silica is dried for a time period rangingfrom about 5 hours to about 24 hours and a weight loss on drying of thedried support is less than about 2 wt. %.

A sixth embodiment which is the method of any of the first through fifthembodiments wherein the methanol is present in an amount ranging fromabout 2 times to about 3 times the weight of the dried support.

A seventh embodiment which is the method of any of the first throughsixth embodiments wherein the methanol has a water content of less thanabout 0.1 wt. %.

An eighth embodiment which is the method of any of the first throughseventh embodiments wherein the silica is characterized by a surfacearea of from about 250 m²/g to about 1000 m²/g and a pore volume ofgreater than about 1.0 cm³/g.

A ninth embodiment which is the method of any of the first througheighth embodiments wherein the titanium alkoxide comprises titaniumn-propoxide.

A tenth embodiment which is the method of any of the first through ninthembodiments wherein the titanium alkoxide is present in an amount offrom about 0.1 wt. % to about 10 wt. % by total weight of the catalyst.

An eleventh embodiment which is the method of any of the second throughtenth embodiments wherein the chromium-containing compound comprisesbasic chromium acetate.

A twelfth embodiment which is the method of any of the second througheleventh embodiments wherein the chromium-containing compound is presentin an amount of from about 0.1 wt. % to about 10 wt. % by total weightof the catalyst.

A thirteenth embodiment which is the method of any of the fourth throughtwelfth embodiments wherein an amount of volatile organic compounds(VOC) emitted during calcining at a temperature in the range of fromabout 400° C. to about 1000° C. for a time period of from about 30minutes to about 24 hours is reduced by from about 50% to about 100%when compared to the amount of VOC emitted during calcining of anotherwise similar catalyst prepared without the addition of water.

A fourteenth embodiment which is the method of any of the fourth throughthe thirteenth embodiments wherein an amount of volatile organiccompounds (VOC) emitted during calcining at a temperature in the rangeof from about 400° C. to about 1000° C. for a time period of from about30 minutes to about 24 hours is less than about 2 wt. %.

A fifteenth embodiment which is a method comprising a) drying a silicasupport material at temperature in the range of from about 150° C. toabout 220° C. to form a dried support; b) contacting the dried supportwith a solution comprising methanol containing less than 0.1 wt. % waterand basic chromium acetate to form a chrominated, slurried support; c)cooling the chrominated, slurried support to a temperature of less thanabout 60° C. to form a cooled slurried support; d) contacting the cooledslurried support with titanium n-propoxide to form a titanated slurriedsupport; e) thermally treating the titanated slurried support byincreasing the temperature of the titanated support to 60° C. to 70° C.;f) prior to complete removal of methanol, contacting the titanatedslurried support with water in an amount ranging from about 0.1 moles toabout 10 moles per mole of titanium to produce a mixture; g) thermallytreating the mixture by heating the mixture to a temperature of about150° C. to about 220° C. for a time period of from about 5 hours toabout 30 hours to form a precatalyst; and h) calcining the precatalystat a temperature in the range of from about 400° C. to about 1000° C.for a time period of from about 30 minutes to about 24 hours to form apolymerization catalyst.

A sixteenth embodiment which is the method of the fifteenth embodimentwherein the support is dried to a weight loss on drying of less thanabout 2 wt. %, an amount of chromium is from about 0.5 wt. % to about1.5 wt. % based on a total weight of the polymerization catalyst, anamount of titanium is from about 1 wt. % to about 5 wt. % based on atotal weight of the polymerization catalyst, and the amount of wateradded in step f) is from about 2 moles to about 5 moles per mole oftitanium.

A seventeenth embodiment which is the method of any of the fifteenththrough sixteenth embodiments wherein the precatalyst is calcined at atemperature in the range of from about 500° C. to about 700° C. for atime period of from about 4 hours to about 12 hours.

An eighteenth embodiment which is a method comprising: a) drying asilica support at temperature in the range of from about 150° C. toabout 220° C. to form a dried support; b) contacting the dried supportwith a chromium-containing compound to form a chrominated support; c)contacting the chrominated support with a solvent to form a slurriedsupport; d) cooling the slurried support to a temperature of less thanabout 60° C. to form a cooled support; e) contacting the cooled supportwith a titanium-containing compound to form a titanated support; f)thermally treating the titanated support by increasing the temperatureof the titanated support to the boiling point of the solvent; g) priorto reaching the boiling point of the solvent, contacting the titanatedsupport with water in an amount ranging from about 0.1 moles to about 10moles per mole of titanium to produce a mixture; h) thermally treatingthe mixture by heating the mixture to a temperature of about 150° C. fora time period of from about 5 hours to about 30 hours to form aprecatalyst; and i) calcining the precatalyst at a temperature in therange of from about 400° C. to about 1000° C. for a time period of fromabout 30 minutes to about 24 hours to form a polymerization catalyst

A nineteenth embodiment which is the method of the eighteenth embodimentwherein the solvent comprises methanol having less than about 0.1 wt. %water.

A twentieth embodiment which is the method of any of the eighteenththrough nineteenth embodiments wherein the titanium-containing compoundcomprises titanium n-propoxide.

A twenty-first embodiment which is the method of any of the eighteenththrough twentieth embodiments wherein the silica support ischaracterized by a surface area of from about 250 m²/g to about 1000m²/g and a pore volume of greater than about 1.0 cm³/g.

A twenty-second embodiment which is a method comprising a) drying asupport material at temperature in the range of from about 150° C. toabout 220° C. to form a dried support; b) contacting the dried supportwith a solvent to form a slurried support; c) subsequent to b), coolingthe slurried support to a temperature of less than about 50° C. to forma cooled support; d) contacting the cooled support with atitanium-containing compound to form a titanated support; e) contactingthe titanated support with a chromium-containing compound to form achrominated support; f) thermally treating the chrominated support byincreasing the temperature of the chrominated support to the boilingpoint of the solvent; g) prior to reaching the boiling point of thesolvent, contacting the chrominated support with water in an amountranging from about 0.1 moles to about 10 moles per mole of titanium toproduce a mixture; and h) thermally treating the mixture by heating themixture to a temperature of equal to or greater than about 150° C. for atime period of from about 5 hours to about 30 hours to yield aprecatalyst.

A twenty-third embodiment which is the method of the twenty-secondembodiment further comprising calcining the precatalyst at a temperaturein the range of from about 400° C. to about 1000° C. for a time periodof from about 30 minutes to about 24 hours to form a polymerizationcatalyst.

A twenty-fourth embodiment which is the method of any of thetwenty-second through twenty-third embodiments wherein the silica isdried for a time period ranging from about 5 hours to about 24 hours.

A twenty-fifth embodiment which is the method of any of thetwenty-second through twenty-fourth embodiments wherein the solvent ispresent in an amount ranging from about 2 times to about 3 times theweight of the dried support.

A twenty-sixth embodiment which is the method of any of thetwenty-second through twenty-fifth embodiments wherein step (d) isperformed under mixing conditions for efficient dispersal of thetitanium alkoxide.

A twenty-seventh embodiment which is the method of any of thetwenty-second through twenty-sixth embodiments wherein the solventcomprises methanol having a water content of less than about 0.1 wt. %.

A twenty-eighth embodiment which is the method of any of thetwenty-second through twenty-seventh embodiments wherein the supportmaterial comprises silica.

A twenty-ninth embodiment which is the method of the twenty-eighthembodiment wherein the silica is characterized by a surface area of fromabout 250 m²/g to about 1000 m²/g and a pore volume of greater thanabout 1.0 cm³/g.

A thirtieth embodiment which is the method of any of the twenty-secondthrough twenty-ninth embodiments wherein the titanium-containingcompound comprises titanium n-propoxide.

A thirty-first embodiment which is the method of any of thetwenty-second through thirtieth embodiments wherein thetitanium-containing compound is present in an amount of from about 0.1wt. % to about 10 wt. % by total weight of the catalyst.

A thirty-second embodiment which is the method of any of thetwenty-second through thirty-first embodiments wherein thechromium-containing compound comprises basic chromium acetate.

A thirty-third embodiment which is the method of the thirty-secondembodiment wherein the chromium-containing compound is present in anamount of from about 0.1 wt. % to about 10 wt. % by total weight of thecatalyst.

A thirty-fourth embodiment which is a method comprising a) drying asupport material at temperature in the range of from about 150° C. toabout 220° C. to form a dried support; b) contacting the dried supportwith a solvent to form a slurried support; c) subsequent to b), coolingthe slurried dried support to a temperature of less than about 50° C. toform a cooled support; d) contacting the cooled support with achromium-containing compound to form a chrominated support; e)contacting the chrominated support with a titanium-containing compoundto form a titanated support; f) thermally treating the titanated supportby increasing the temperature of the titanated support to the boilingpoint of the solvent; g) prior to reaching the boiling point of thesolvent, contacting the titanated support with water in an amountranging from about 0.1 moles to about 10 moles per mole of titanium toproduce a mixture; and h) thermally treating the mixture by heating themixture to a temperature equal to or greater than about 150° C. for atime period of from about 5 hours to about 30 hours to yield aprecatalyst.

A thirty-fifth embodiment which is the method of the thirty-fourthembodiment further comprising calcining the precatalyst at a temperaturein the range of from about 400° C. to about 1000° C. for a time periodof from about 30 minutes to about 24 hours to form a polymerizationcatalyst.

A thirty-sixth embodiment which is the method of any of thethirty-fourth through thirty-fifth embodiments wherein the solventcomprises methanol having less than about 0.1 wt. % water.

A thirty-seventh embodiment which is the method of any of thethirty-fourth through thirty-sixth embodiments wherein the supportmaterial comprises silica.

A thirty-eighth embodiment which is the method of the thirty-seventhembodiment wherein the silica is characterized by a surface area of fromabout 250 m²/g to about 1000 m²/g and a pore volume of greater thanabout 1.0 cm³/g.

A thirty-ninth embodiment which is the method of any of thethirty-fourth through thirty-eighth embodiments wherein thetitanium-containing compound comprises titanium n-propoxide.

A fortieth embodiment which is the method of any of the thirty-fourththrough thirty-ninth embodiments wherein the titanium-containingcompound is present in an amount of from about 0.1 wt. % to about 10 wt.% by total weight of the catalyst.

A forty-first embodiment which is the method of any of the thirty-fourththrough fortieth embodiments wherein the chromium-containing compoundcomprises chromium (III) acetate hydroxide.

A forty-second embodiment which is the method of any of thethirty-fourth through forty-first embodiments wherein thechromium-containing compound is present in an amount ranging from about0.1 wt. % to about 10 wt. % by total weight of the catalyst.

A forty-third embodiment which is a method comprising a) drying a silicasupport material at temperature in the range of from about 150° C. toabout 220° C. to form a dried support; b) contacting the dried supportwith a chromium-containing compound to form a chrominated support; c)contacting the chrominated support with a solvent to form a slurriedsupport; d) cooling the slurried support to a temperature of less thanabout 50° C. to form a cooled support; e) contacting the cooled supportwith a titanium-containing compound to form a titanated support; f)thermally treating the titanated support by increasing the temperatureof the titanated support to the boiling point of the solvent; g) priorto reaching the boiling point of the solvent, contacting the titanatedsupport with water in an amount ranging from about 0.1 moles to about 10moles per mole of titanium to produce a mixture; h) thermally treatingthe mixture by heating the mixture to a temperature of equal to orgreater than about 150° C. for a time period of from about 5 hours toabout 30 hours to form a precatalyst; and i) calcining the precatalystat a temperature in the range of from about 400° C. to about 1000° C.for a time period of from about 30 minutes to about 24 hours to form apolymerization catalyst

A forty-fourth embodiment which is a method comprising a) drying asilica support material at temperature in the range of from about 150°C. to about 220° C. to form a dried support; b) contacting the driedsupport with a solvent to form a slurried support; c) contacting theslurried dried support with a chromium-containing compound to form achrominated support; d) subsequent to c), cooling the chrominatedsupport to a temperature of less than about 50° C. to form a cooledsupport; e) contacting the cooled support with a titanium-containingcompound to form a titanated support; f) thermally treating thetitanated support by increasing the temperature of the titanated supportto the boiling point of the solvent; g) prior to reaching the boilingpoint of the solvent, contacting the titanated support with water in anamount ranging from about 0.1 moles to about 10 moles per mole oftitanium to produce a mixture; h) thermally treating the mixture byheating the mixture to a temperature of equal to or greater than about150° C. for a time period of from about 5 hours to about 30 hours toform a precatalyst; and i) calcining the precatalyst at a temperature inthe range of from about 400° C. to about 1000° C. for a time period offrom about 30 minutes to about 24 hours to form a polymerizationcatalyst.

A forty-fifth embodiment which is a method comprising a) obtaining achromium-silica-titania polymerization catalyst; b) slurrying thechromium-silica-titania catalyst in methanol wherein the methanolcontains less than about 0.1 wt. % water to produce a slurried catalyst;c) cooling the slurried catalyst to a temperature of less than about 50°C. to produce a cooled slurried catalyst; d) thermally treating thecooled slurried catalyst by increasing the temperature of the cooledsupport to the boiling point of the solvent; e) prior to reaching theboiling point of the solvent, contacting the cooled slurried catalystwith water in an amount ranging from about 0.1 moles to about 10 molesper mole of titanium to produce a mixture; f) thermally treating themixture by heating the mixture to a temperature of equal to or greaterthan about 150° C. for a time period of from about 5 hours to abouthours to form a precatalyst; and g) calcining the precatalyst at atemperature in the range of from about 400° C. to about 1000° C. for atime period of from about 30 minutes to about 24 hours to form apolymerization catalyst.

A forty-sixth embodiment which is the method of the forty-fifthembodiment wherein an amount of volatile organic compounds (VOC) emittedduring the calcining is reduced by from about 50% to about 100% whencompared to the amount of VOC emitted during calcining of an otherwisesimilar catalyst.

A forty-seventh embodiment which is a method comprising a) drying asilica support material at temperature in the range of from about 150°C. to about 220° C. to form a dried support; b) contacting the driedsupport with a solvent comprising a chromium-containing compound to forma chrominated, slurried support; c) cooling the chrominated, slurriedsupport to a temperature of less than about 50° C. to form a cooledsupport; d) contacting the cooled support with a titanium-containingcompound to form a titanated support; e) thermally treating thetitanated support by increasing the temperature of the titanated supportto the boiling point of the solvent; f) prior to reaching the boilingpoint of the solvent, contacting the titanated support with water in anamount ranging from about 0.1 moles to about 10 moles per mole oftitanium to produce a mixture; g) thermally treating the mixture byheating the mixture to a temperature of equal to or greater than about150° C. for a time period of from about 5 hours to about 30 hours toform a precatalyst; and h) calcining the precatalyst at a temperature inthe range of from about 400° C. to about 1000° C. for a time period offrom about 30 minutes to about 24 hours to form a polymerizationcatalyst.

A forty-eighth embodiment which is the method of the first embodimentfurther comprising, prior to the conclusion of step (e), wherein theconclusion of step (e) results in the removal of methanol from thesupport, adding a chromium-containing compound to the support to form aprecatalyst.

A forty-ninth embodiment which is the method of the forty-eighthembodiment further comprising, prior to, during, or after any one ormore of steps (a)-(e), adding a chromium-containing compound to thesupport to form a precatalyst.

While various embodiments have been shown and described, modificationsthereof can be made by one skilled in the art without departing from thespirit and teachings of the disclosure. The embodiments described hereinare exemplary only, and are not intended to be limiting. Many variationsand modifications of the disclosure disclosed herein are possible andare within the scope of the disclosure. Where numerical ranges orlimitations are expressly stated, such express ranges or limitationsshould be understood to include iterative ranges or limitations of likemagnitude falling within the expressly stated ranges or limitations(e.g., from about 1 to about 10 includes, 2, 3, 4, etc.; greater than0.10 includes 0.11, 0.12, 0.13, etc.). Use of the term “optionally” withrespect to any element of a claim is intended to mean that the subjectelement is required, or alternatively, is not required. Bothalternatives are intended to be within the scope of the claim. Use ofbroader terms such as comprises, includes, having, etc. should beunderstood to provide support for narrower terms such as consisting of,consisting essentially of, comprised substantially of, etc.

Accordingly, the scope of protection is not limited by the descriptionset out above but is only limited by the claims which follow, that scopeincluding all equivalents of the subject matter of the claims. Each andevery claim is incorporated into the specification as an embodiment ofthe present disclosure. Thus, the claims are a further description andare an addition to the embodiments of the present disclosure. Thediscussion of a reference in the disclosure is not an admission that itis prior art to the present disclosure, especially any reference thatmay have a publication date after the priority date of this application.The disclosures of all patents, patent applications, and publicationscited herein are hereby incorporated by reference, to the extent thatthey provide exemplary, procedural or other details supplementary tothose set forth herein.

What is claimed is:
 1. A method comprising: a) drying a silica supportat a temperature in a range of from about 150° C. to about 220° C. toform a dried support; b) contacting the dried support with achromium-containing compound to form a chrominated support; c)contacting the chrominated support with a solvent to form a slurriedsupport; d) cooling the slurried support to a temperature of less thanabout 60° C. to form a cooled support; e) contacting the cooled supportwith a titanium-containing compound to form a titanated support; f)thermally treating the titanated support by increasing the temperatureof the titanated support to the boiling point of the solvent; g) priorto removing all of the solvent, contacting the titanated support withwater in an amount ranging from about 0.1 moles to about 10 moles permole of titanium to produce a mixture; h) thermally treating the mixtureby heating the mixture to a temperature of about 150° C. for a timeperiod of from about 5 hours to about 30 hours to form a precatalyst;and i) calcining the precatalyst at a temperature in the range of fromabout 400° C. to about 1000° C. for a time period of from about 30minutes to about 24 hours to form a polymerization catalyst.
 2. Themethod of claim 1 wherein the solvent comprises methanol having lessthan about 0.1 wt. % water.
 3. The method of claim 1 wherein thetitanium-containing compound comprises titanium n-propoxide.
 4. Themethod of claim 2 wherein the titanium-containing compound comprisestitanium n-propoxide.
 5. The method of claim 1 wherein thechromium-containing compound comprises basic chromium acetate.
 6. Themethod of claim 4 wherein the chromium-containing compound comprisesbasic chromium acetate.
 7. The method of claim 6 wherein the slurriedsupport is cooled to a temperature of less than about 50° C. to form thecooled support.
 8. The method of claim 6 wherein the slurried support iscooled to a temperature of less than about 40° C. to form the cooledsupport.
 9. The method of claim 1 wherein step (e) is performed undervigorous mixing conditions suitable to provide for efficient dispersalof the titanium-containing compound.
 10. The method of claim 8 whereinstep (e) is performed under vigorous mixing conditions suitable toprovide for efficient dispersal of the titanium-containing compound. 11.The method of claim 2 wherein the solvent is present in an amountranging from about 2 times to about 3 times weight of the dried support.12. The method of claim 10 wherein the solvent is present in an amountranging from about 2 times to about 3 times weight of the dried support.13. The method of claim 11 wherein the support material is dried for atime period ranging from about 5 hours to about 24 hours.
 14. The methodof claim 12 wherein the support is dried in an inert atmosphere.
 15. Themethod of claim 1 wherein step (c) is repeated from about 2 to about 10times.
 16. The method of claim 1 wherein the silica support containsgreater than about 50% silica and the silica support is characterized bya surface area of from about 250 m²/g to about 1000 m²/g and a porevolume of from about 1.0 cm³/gram to about 2.5 cm³/gram.
 17. The methodof claim 1 wherein calcining the precatalyst is in air, oxygen, inertgases, carbon monoxide or a combination thereof.
 18. The method of claim1 wherein the amount of water added in step g) is from about 2 moles toabout 5 moles per mole of titanium.
 19. The method of claim 1 wherein anamount of volatile organic compounds (VOC) emitted during the calciningis reduced by from about 50% to about 100% when compared to the amountof VOC emitted during calcining of a similar precatalyst preparedwithout the addition of water to the titanated slurried support.
 20. Themethod of claim 1 wherein an amount of volatile organic compounds (VOC)emitted during calcining is less than about 2 wt. %.